Children who are hard of hearing (CHH) who wear hearing aids have experienced improved early childhood developmental outcomes due to early identification and intervention compared to previous generations, but may still face delays in specific abilities related to inconsistent auditory experience. Early language and cognitive abilities form the foundation for listening and learning in classrooms during elementary schools. Therefore, CHH who have deficits in these skills may face significant academic and social challenges as they enter school. However, the effect of inconsistent auditory experience during early childhood on the ability to understand speech in noise and reverberation has not been widely studied in CHH who wear hearing aids. The long-term goal of this research program is to optimize amplification and speech understanding in CHH by identifying the underlying processes that support listening in academic and social situations. The objective of this proposal is to examine how inconsistent auditory experience during early childhood affects speech understanding in noise and reverberation and on complex tasks that require cognitive processing. The current proposal will also examine how linguistic and cognitive skills may help minimize the negative consequences of limited auditory experience by supporting listening under degraded acoustic conditions. The central hypothesis of the current proposal is that inconsistent early auditory experience at age 3 will negatively impact speech understanding in noise and reverberation in CHH at school age. Three specific aims are proposed to test this theory: Aim 1. To test the hypothesis that inconsistent auditory experience of CHH prior to entering school results in poorer speech recognition at school-age and that cognitive and linguistic skills at 1st grade will mediate this relationship at 3rd grade. Aim 2. To test the hypothesis that acoustic factors and working memory skills affect listening in modulated noise and reverberation in children. Aim 3. To determine the extent to which concurrent memory, EF, and linguistic skills are related to speech perception and discrimination in CHH, and to evaluate how variations in listening task demands moderate that relationship. In Aim 1, aided speech audibility, amount of daily hearing aid use, and the quantity and quality of parental language input at age 3 will be used to predict sentence recognition in classroom levels of noise and reverberation at 1st grade. Aided audibility, hearing aid use and 1st grade language skills will then be used to predict speech recognition in degraded conditions at 3rd grade. In Aim 2, audibility and working memory will be used to predict how well children can use speech information from brief gaps of modulated noise to reconstruct the speech signal in noise and reverberation. In Aim 3, concurrent language and cognitive abilities will be used to predict listening on a multi-talker speech recognition and gated-sentence recognition tasks. The data generated from this proposal will allow optimization of amplification based on the listening environment and lead to interventions that target the skills the support listening and learning in realistic environments.